Re: Last Call: <draft-ietf-6man-rfc4291bis-07.txt> (IP Version 6 Addressing Architecture) to Internet Standard

Fernando Gont <fgont@si6networks.com> Fri, 24 February 2017 03:15 UTC

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Subject: Re: Last Call: <draft-ietf-6man-rfc4291bis-07.txt> (IP Version 6 Addressing Architecture) to Internet Standard
To: David Farmer <farmer@umn.edu>, Lorenzo Colitti <lorenzo@google.com>
References: <20170221001940.GB84656@Vurt.local> <068ce975-8b1e-a7c5-abba-2bfc1d904d70@gmail.com> <20170221101339.GC84656@Vurt.local> <CAKD1Yr33oQb=gMGaEM++hLgmMtxMdihiDrUihEsjs63vy8qRbA@mail.gmail.com> <54c81141-e4f5-4436-9479-9c02be6c09bb@Spark> <CAKD1Yr28iQHt0iuLvR3ndrT3Hfct=4k9dxjJeu3MAjDjOogEvA@mail.gmail.com> <CAL9jLaZgTp++PJ9KGHEWuPoVm6t3b8QfVDCEhz5h4fv-0fuUAA@mail.gmail.com> <CAKD1Yr3SbR=xt3RPu7+q1o14wKuUuwUc6oG+BgZtEK1O+m5sWw@mail.gmail.com> <4936e96b-fc82-4de0-9188-ced9547deb2f@Spark> <CAKD1Yr3K+SJb_4ksZ96yNypVKJE-fXopuVaXNhhKp1gkh1=QEg@mail.gmail.com> <20170222144147.GC89584@hanna.meerval.net> <7960ff2d-359f-429c-6e82-ef592f90bf53@gmail.com> <CAKD1Yr1W+AVt4Dixo9epB5VazxBsVMD+mrshwaE=n7SuX6eGDw@mail.gmail.com> <5ce34926-6bde-6410-9b1e-3f61e48e9a1d@gmail.com> <CAKD1Yr1yRTUPVTTicaTkA8fAFxHiHxdLG8ZzEHjCUDDzKg5zJg@mail.gmail.com> <CAN-Dau0xpjB4Z8CgSfW0W7y4F_wnXNS+Ws1UNBC-YnBDrPiTjQ@mail.gmail.com>
From: Fernando Gont <fgont@si6networks.com>
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On 02/23/2017 07:43 PM, David Farmer wrote:
> 
> 
> On Wed, Feb 22, 2017 at 10:16 PM, Lorenzo Colitti <lorenzo@google.com
> <mailto:lorenzo@google.com>> wrote:
> 
>     Help he understand, then. There is widely-deployed code that assumes
>     that the interface ID is 64 and does not work on anything other than
>     64 bit prefix lengths. Currently that code is correct on all unicast
>     space. If you change RFC 4291, won't that code be incorrect?
> 
> 
> OK, what if we said something like this;
> 
>    IPv6 unicast routing is based on prefixes of any valid length up to
>    128 [BCP198]. However, all implementations of IPv6 are REQUIRED to
>    support an IID length of 64 bits, other IID lengths are OPTIONAL.
>    Subnet prefixes of /64 are RECOMMENDED for general purpose use,
>    subnet prefixes of /127 are RECOMMENDED for point-to-point router
>    links [RFC6164], other subnet prefix lengths are NOT RECOMMENDED,
>    as their use could be incompatible with some implementations of IPv6.
>    The rationale for the 64 bit boundary in IPv6 addresses can be found
>    in [RFC7421].

I'd remove a few sentences here, as in:

   IPv6 unicast routing is based on prefixes of any valid length up to
   128 [BCP198]. Subnet prefixes of /64 are RECOMMENDED for general
   purpose use, subnet prefixes of /127 are RECOMMENDED for point-
   to-point router links [RFC6164]. The rationale for the 64 bit
   boundary in IPv6 addresses can be found in [RFC7421].

Thanks,
-- 
Fernando Gont
SI6 Networks
e-mail: fgont@si6networks.com
PGP Fingerprint: 6666 31C6 D484 63B2 8FB1 E3C4 AE25 0D55 1D4E 7492